Headlines

Emergence in France of a new plasmid-mediated resistance to colistin (mcr-1 gene) in Enterobacteriaceae

Plasmid-mediated colistin resistance (mcr-1 gene) in Enterobacteriaceae was first detected in China in late 2015. It poses a public health risk because colistin is one of the few antibiotics still effective against carbapenemase-producing Enterobacteriaceae (CPE) strains—the primary emerging Highly Resistant Bacteria (HRB). Its plasmid-mediated nature allows it to be very easily transferred between bacteria.Colistin-resistant strains have since been isolated by several other countries in the environment, food, animals, and also in humans: particularly in China (the leading user of colistin in animal health), in some European countries (including Germany and the United Kingdom), in Canada, and more recently in the United States. The international spread of this resistance gene, particularly in Europe, is thus confirmed, as highlighted in March 2016 in a summary published by the European Centre for Disease Prevention and Control (ECDC). A rapid risk assessment regarding this emergence was published by the ECDC on June 15, 2016. In France since July 2016, several strains of Enterobacteriaceae carrying the mcr-1 plasmid-mediated colistin resistance gene have been identified. These include either strains identified during retrospective studies (2 strains in New Caledonia, 1 in Marseille, and 1 in Angers) or strains isolated in September/October from patients hospitalized in 4 healthcare facilities (4 confirmed cases: 2 in Auvergne-Rhône-Alpes and 2 in Île-de-France). These 4 strains were derived from screening samples. These patients were isolated during their hospitalization, placed under enhanced contact precautions (ECP), and contact patients associated with these cases were screened, in accordance with the recommendations of the High Council for Public Health (HCSP) regarding the management of patients carrying a BHRe. No secondary cases were identified.This detection in humans in France was expected given the circulation of this resistance mechanism for several years in other countries and its detection by the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) in animals and in several types of food products. This new emergence currently has no clinical impact on patients but requires close monitoring. Controlling its spread is a major challenge to limit the risk of eventually seeing the emergence of strains that are completely resistant to antibiotics, which would cause infections that could then not be treated